* update model save load

* first add

* update model save and load

* update train.py

* update LaneNet model saving and loading

* adapt slim to paddle-1.8

* update distillation save and load

* update nas model save and load

* update model load op

* update utils.py

* update load_model_utils.py

* update model saving and loading

* add_vdl

* Update docs for visualdl.

* release change log

* update readme

* update readme

* upload fast-scnn image

* update readme

* update readme

* replace fluid.layers.data

* update api fluid.data and fluid.io.DataLoader
Co-authored-by: NLielinJiang <jianglielin@baidu.com>
Co-authored-by: NLielinJiang <50691816+LielinJiang@users.noreply.github.com>

* add prune distill nas

* update readme

* update readme

* remove debug code